It happened at the former Town 'n Country convenience store in the 3700 block of Fayetteville Street, across from Hillside High School.
It appeared that the man died after getting trapped inside the duct work while trying to break into the store, which closed several months ago.
Insurance adjusters were on the roof of the building when they made the discovery and called 911.
Caller: "We're at the Town 'n Country at the convenient store. It's closed down. We're the insurance company and we went up on the roof to check … they got a claim for some stuff for copper for the units. We went up on the roof, and there appears to be part of a dead body up here."
Dispatcher: "It's a human body?"
Caller: "Yea. All we can see is the legs, the feet and the socks and it appears to be a human body. If not, it's a really good model but it looks old and dilapidated, like it's been there awhile."
There's still no word on the man's identity.